It's a scenario NASA hopes to never to face: An astronaut in
distress in a hostile environment in need of a rescue. But in this emergency,
the victims are mannequins and the rescuers are professional divers and astronauts
on the ocean floor practicing exactly how such a scene might play out on the
moon or asteroid.

The mock space rescue is just one of several simulations
performed this week on the by the 14th
expedition of the NASA Extreme Environment Mission Operations, or NEEMO.
The divers and astronauts are midway through a two-week mission that began May
10.

Canadian Space Agency astronaut Chris Hadfield, a veteran
spacewalker, is leading the expedition in the Aquarius Underwater Laboratory,
which rests more than 62 feet (18 meters) below the ocean's surface off the
coast of Key Largo in the Florida Keys. His crew, which spoke to reporters from
the seafloor in a Friday teleconference, plans to return to the surface on
Sunday.

Space 'rescue' at sea

The crewmembers live aboard Aquarius, which is pressurized
to a level that is slightly higher than the pressure in car tires, and venture
out on simulated spacewalks, called extravehicular activities (EVAs).

EVAs were done to simulate removing the mockup of the Lunar
Electric Rover from the lander, retrieve small payloads from the lander and
the ocean floor and simulate the transfer of an incapacitated astronaut from
the ocean floor to the deck of the craft.

"If you're out on a spacewalk on Mars and you're trying
to pick something up and wrench your back, or if you have a heart attack, or if
your suit malfunctions and you go unconscious, we have to at least protect for
one level of failure," Hadfield told SPACE.com. "How can you get a
person in your spacesuit back into the habitat or rover if they can't do it
themselves?"

Hadfield and other NEEMO crewmembers used each other and
weighted mannequins to test different ways to execute a rescue.

Aquanauts from spaceHadfield previously conducted two
spacewalks and operated the International Space Station's robotic arm, known as
Canadarm2, during the space shuttle's STS-100 mission in April 2001. He also
worked extensively with the shuttle's robotic Canadarm on STS-74 in 1995.

Other team members include flight surgeon Thomas Marshburn,
Lunar Electric Rover Deputy Project Manager Andrew Abercromby and Steve
Chappell, a research scientist. James Talacek and Nate Bender of the University
of North Carolina at Wilmington are habitat technicians and provide engineering
support.

"We've been extremely busy and extremely
productive," Hadfield said. "We have done over 50 spacewalks in two
weeks. The reason we're down here is to simulate spaceflight."

The NEEMO 14 mission is using the ocean floor to simulate
aspects of another
planet's surface and a low-gravity environment. The objective is to test
concepts for future planetary exploration missions.

"This is the closest simulation I've had," Thomas
Marshburn, NEEMO 14 team member, NASA astronaut and flight surgeon, told
SPACE.com. "It certainly is alien ? we're moving around as if we're in an
altered gravity environment. It feels like a dangerous environment, which is
what space is."In October 2009, a team of aquanauts prepared for the NEEMO
14 expedition by placing mockups of a lander, rover and small crane that
simulates a robotic arm near the Aquarius laboratory. The rover and lander
mockups are comparable in size to vehicles that NASA is considering for future
planetary exploration.

"We're simulating different gravities," Hadfield
said. "With the water, you can simulate being on Mars, being on the moon,
or even on an asteroid."

The lander mockup is wider than the entire length of a
school bus, and is almost three times as high. It measures 45 feet (13.7
meters) wide and 28 feet (8.5 meters) high, including a 10-foot-high
(3-meter-high) crane. The rover mockup is slightly larger than a full-size SUV,
standing at approximately eight feet (2.4 meters) tall and 14 feet (4.3 meters)
long. The aquanauts also donned center of gravity (CG) rigs and extra weights
to simulate the CG and weight of spacesuits in reduced gravity.

"We're testing spacesuits for different levels of
gravity," Hadfield said. "We want to explore an asteroid, which is
almost no gravity. But, how do you control where you are if you can't grab onto
man-made handholds or have places to put your feet?"

Using the special rigs, the aquanauts can evaluate where the
distribution of weight should be for future spacesuit designs.

"We're finding that a center of gravity that is
completely wrong on Earth ? one that would just give you a backache ? may help
you with some of the tasks when you feel much lighter, when you don't have the
weight of the Earth pulling you down," Hadfield said.

By operating and testing these developing technologies,
NEEMO crewmembers will be able to provide information and valuable feedback to
NASA engineers following the mission.

Life beneath the sea

The crew has also been performing life science experiments
that are focused on human behavior, performance and physiology. The mission
also includes a study of autonomous crew work.

For instance, beginning in the second half of the mission,
the crew simulated periods of limited communication between the crew and the
mission control center, much like what could potentially happen during missions
to the
moon or Mars.

"For the second week, we simulated that we were so far
away that it takes 20 minutes when I send a message for it to arrive in your
ear or your laptop," Hadfield said. "We call it autonomous operations
and it increases our level of isolation. It's the six of us with each other
with only peripheral help from outside."

For Hadfield, the NEEMO mission represents an important
stepping stone at a crucial time in space exploration.

"We're just now at the point where we're starting to
permanently leave the planet," he said. "We are forging the first
steps away from Earth. And it isn't easy. Every little step we take in
exploration down here just opens up possibilities of human understanding, human
enrichment and human development of where we are in the universe."